Contactless electricity supply device

Abstract

A contactless electric power supply device 100 to charge a battery 28 of a vehicle includes a power transmitting circuit 101 having a power transmitting coil 12 and a charging circuit 201 having a power receiving coil 22 . An electric power is transmitted from power transmitting coil 12 to power receiving coil 22 in a contactless manner. When the vehicle approaches power supply device 100 , a trial power supply in which a electric power transmission through a minute electric power is carried out is executed and a power transmission efficiency from power transmitting coil 12 to power receiving coil 22 is estimated on a basis of a current flowing through power transmitting circuit 101 . From this power transmission efficiency, a determination of whether power receiving coil 22 falls in a range in which battery 28 is chargeable with respect to power transmitting coil 12 is made.

The invention claimed is: 
     
       1. A contactless power supply device for transmitting an electric power from a first coil to a second coil in a contactless manner by at least a magnetic coupling, comprising:
 a power transmitting circuit including the first coil; 
 a sensor configured to measure a current flowing through the power transmitting circuit or to measure a voltage applied to the power transmitting circuit; 
 a battery providing a power source of a vehicle; 
 a charging circuit including the second coil and configured to charge the battery; 
 an informing device; and 
 a control section in communication with the sensor, the control section being configured to:
 determine an input electric power of the power transmitting circuit from at least either one of values from a detected current or a detected voltage detected by the sensor; 
 estimate a power transmission efficiency from the first coil to the second coil on a basis of a correlation between the power transmission efficiency from the first coil to the second coil and the input electric power such that as the input electric power becomes higher, the estimated power transmission efficiency becomes higher; 
 determine that a positional deviation between the first coil and the second coil falls in a range in which the battery is chargeable, in a case where the power transmission efficiency estimated by the control section is higher than a predetermined value; 
 based on the determination that the positional deviation falls in the range in which the battery is chargeable, control the informing device to indicate that the charging is allowed; and 
 in response to the indication that the charging is allowed, enable a user of the vehicle to confirm via the informing device that the control section controls the charging circuit to charge the battery. 
 
 
     
     
       2. The contactless power supply device as claimed in  claim 1 , further comprising a switch connected between the battery and the charging circuit wherein the switch is in an off state during a traveling of the vehicle. 
     
     
       3. The contactless power supply device as claimed in  claim 1 , wherein the control section is further configured to estimate the power transmission efficiency during a traveling of the vehicle. 
     
     
       4. The contactless power supply device as claimed in  claim 1 , wherein a trial power supply to supply the electric power through a minute electric power is carried out and, while the trial power supply is carried out, the estimation of the power transmission efficiency is carried out. 
     
     
       5. The contactless power supply device as claimed in  claim 1 , wherein, when a distance between the vehicle and the first coil becomes shorter than a predetermined distance, a trial power supply to supply electric power through a minute electric power is carried out and, while the trial power supply is carried out, the estimation of the power transmission efficiency is carried out. 
     
     
       6. A contactless power supply device for transmitting an electric power from a first coil to a second coil in a contactless manner by at least a magnetic coupling, comprising:
 a power transmitting circuit including the first coil; 
 a sensor configured to measure a current flowing through the power transmitting circuit or to measure a voltage applied to the power transmitting circuit; 
 a battery providing a power source of a vehicle; 
 a charging circuit including the second coil and configured to charge the battery; 
 an informing device; and 
 a controller in communication with the sensor, the controller being configured to:
 determine an input electric power of the power transmitting circuit from at least either one of values from a detected current or a detected voltage detected by the sensor; 
 estimate a power transmission efficiency from the first coil to the second coil on a basis of a correlation between the power transmission efficiency from the first coil to the second coil and the input electric power such that as the input electric power becomes higher, the estimated power transmission efficiency becomes higher; 
 determine that a positional deviation between the first coil and the second coil falls in a range in which the battery is chargeable, in a case where the power transmission efficiency estimated by the controller is higher than a predetermined value; 
 based on the determination that the positional deviation falls in the range in which the battery is chargeable, control the informing device to indicate that the charging is allowed; and 
 in response to the indication that the charging is allowed, enable a user of the vehicle to confirm via the informing device that the controller controls the charging circuit to charge the battery.